Thanks for the examples, everyone! It does look like we're picking up something funny via JavaScript there. We're looking into what can be done in this particular case. In the meantime, keep in mind that 404 errors of URLs that are invalid (like these appear to be) are not something that would affect your site's indexing or ranking, so while I understand that they may be confusing (and I'm sorry for the number of URLs here), it's not something that you'd need to take action on.